Macromolecules can comprise unique sequences of monomers or other moieties that can be used to readily distinguish one macromolecule from another. When a macromolecule is bound to or associated with another entity, that entity can be identified by features of the macromolecule. The entity can be any entity apparent to one to those of skill in the art such as a substrate, a surface, another molecule, a position in an array or any other entity with which a macromolecule can be associated. One can readily identify the entity by identifying the macromolecule.
Of the many features of macromolecules, their structure provides much of their diversity. Generally, their primary structure, i.e. the sequence of their monomers or other moieties, distinguishes one macromolecule from another macromolecule. However, many, if not most, macromolecules comprise further levels of structure, such as secondary, tertiary or even quaternary structure, that can actually hinder the ability of one of skill to identify the primary structure of the macromolecule. To illustrate, a simple macromolecule comprising a primary sequence of features A, B, C, D, E and F can be readily identified if each feature can be recognized one after the other along the primary sequence. However, if that macromolecule were twisted, kinked or folded into a three dimensional structure, as is often the case with naturally occurring macromolecules in solution, the features might not be readily identifiable in their proper sequence. One of skill in the art might not be able to distinguish a macromolecule having the primary structure A, B, F, C, E and D from the primary structure A, B, C, D, E and F due to secondary or tertiary or quaternary structure.
Persons of skill have developed techniques to tease primary structure out of a three dimensional macromolecule. For certain macromolecules, e.g. polynucleotides and polypeptides, chemical techniques for identifying the primary sequence of their features will be familiar to those of skill. In addition, a few techniques for extending or stretching or combing macromolecules have been developed to reduce the complexity of their structures and thereby facilitate the elucidation of primary structure. These techniques have generally involved the application of some force capable of extending the macromolecule. Some techniques have further involved the nonselective fixing of the macromolecule in an extended state, for instance by drying the macromolecule on a surface.
Methods and compositions that facilitate the identification of the primary structure of a macromolecule will further enhance their utility in the fields of macromolecular recognition and macromolecular labeling and other fields.